Tanks of compressed air are commonly employed to provide the necessary air supply for breathing when used in oxygen deficient environments such as underwater and in noxious gas or oxygen-depleted atmospheres. Underwater diving systems and fire fighting systems are but two examples of equipment utilizing compressed air tanks.
Although safety courses are available for amateur divers, a diver can become disoriented easily under water. The diver is in an environment which is very different from his normal environment on land. It is strange to him, particularly in the early stages of the learning process. Thus, it is not surprising that divers frequently forget to look at their watches or air pressure gauge and lose track of their position. If a diver becomes confused, it is not uncommon for him to suffer panic and consume more than the usual amount of air. He becomes inattentive to the time which has elapsed since the dive began and thus loses track of his air supply, which may not be sufficient to return him to the surface or to a safe place on the surface. Even if he reaches the surface, he can drown from physical exhaustion if the air supply is depleted and he is not sufficiently close to land or a boat. The watchword for divers is "plan the dive and dive the plan".
Similarly, firefighters are often placed in environments such as smoke-filled rooms wherein they are unable to see either their watches or a visual signal announcing a reduction in air supply. Just as often they become so involved in completing the critical work at hand that they forget or lose cite of the time elapsed. In so doing they unknowingly subject themselves to a physically injurious, if not fatal, situation.
If the user becomes confused or is excited, it is not uncommon for him to panic and consume more than the usual amount of air thus depleting his supply faster than anticipated. Also, under such circumstances the user often becomes inattentive to the time which has elapsed and loses track of his air supply, which may not be sufficient to return to a safe atmosphere.
Previous attempts to develop a reliable warning device that automatically generates an audible warning signal when the tank air pressure has been reduced to a predetermined low pressure have been unsuccessful. The prior art warning devices, for whatever reason, fail sooner or later to give off the desired audible signal when the predetermined supply level has been reached. Needless to say that an unreliable self-contained breathing apparatus (S.C.B.A.) warning device is a useless warning device.
Accordingly, it is an object of the invention to provide a new and improved warning device for underwater diving equipment or fire fighting equipment and the like, that automatically transmits a signal under water or in a noxious gas atmosphere which will capture the wearer's attention, indicating that a predetermined supply of air remains in the air tank and that he should take action for his personal safety.
It is another object of the invention to provide such a warning device which generates a sound signal that can be readily heard underwater.
It is another object of the invention to provide such a warning device which can be quickly and easily adjusted to a selected trip point so that the warning device will respond to the remaining air supply as predetermined by the wearer or user, indicating a critical point in a diving or working plan.
It is a further object of the invention to provide a new and improved warning device which device can be readily affixed to the users existing equipment without substantial modifications.
Yet another object of the invention is to provide a warning device designed for use in conjunction with conventional air tank pressure gauges and serving as a back warning system such pressure gauges.